Speaker
Dr
Artur Ukleja
(National Centre for Nuclear Research Warsaw)
Description
The LHCb experiment is designed to study B and D decays at the LHC, and as such is
constructed as a forward spectrometer. The large particle density in the
forward region poses extreme challenges to the subdetectors, in terms of hit
occupancies and radiation tolerance. Two methods and their results will be presented
that show no radiation damage of the gaseous straw tube detector after having
received a dose of about 0.2 C/cm2 in the hottest area.
The precision measurements at LHCb require accurate alignment of their elements.
In run-2 of the LHC the full potential of the state-of-the-art alignment system
"RASNIK" is being exploited. Relative movements down to 1 um are being monitored
and will be shown for the first time at this conference. High accuracy of the
RASNIK data allow to track deformations connected with changing magnetic field
configurations, operational interventions and environmental conditions. The
RASNIK system also provides crucial input to the software alignment by
constraining the so-called "weak-modes", like movements in the longitudinal
direction z.
The Outer Tracker subdetector is a gaseous straw tube tracker that measures the
drift time with a resolution of 2.4 ns. This accuracy implies an improvement of
20% with respect to the run-1 performance, thanks to a new strategy used for the
drift time calibration including real-time calibration during data taking deployed
in run-2.
Interestingly, recent studies show that this superb timing resolution can be
combined to measure the time-of-flight of single particles with an accuracy of
0.55 ns. We will show that low momentum protons can be cleanly distinguished
from pions. In addition, these pilot studies show the potential of
distinguishing primary vertices which occur at different times, which will be
crucial for LHCb when operating in the high-luminosity regime as is being
proposed after the phase-II upgrade.
The possibility is being investigated to use the vertex timing for the measurement of the longitudinal
distribution of the unintentional beam population in the nominally empty slots, which requires a timing
precision better than about 2.5 ns.
Summary
State-of-the art hardware alignment systems are being deployed in run-2 of the LHC, to a precision of 1 um
lateral displacement. In addition, very accurate drift time measurements have been achieved with the LHCb straw
tube detector, leading to time-of-flight measurements of protons with a precision of about 500 ps. This
has been made possible thanks to the recent implementation of real time calibration during data taking.
The application of timing information show the use of 4D tracking for future upgrades of LHCb.
Primary author
Niels Tuning
(Nikhef)
Co-author
Dr
Artur Ukleja
(National Centre for Nuclear Research Warsaw)
